Dual tasking affects gait performance but not automaticity in functional gait disorders: A new diagnostic biomarker.

INTRODUCTION: Functional gait disorders (FGDs) are disabling symptoms of Functional Motor Disorders. Clinical observations show improvement with distraction suggesting an association with higher-level control mechanisms. Dual tasking is a valuable tool for exploring the interplay between gait and cognition. Our research question was: how do different dual task paradigms shape spatio-temporal gait parameters in FGDs?. METHODS: In all, 29 patients with FGDs (age 43.48 ± 15.42 years; female 75%) and 49 healthy controls (age 43.33 ± 15.41 years; female 62%) underwent spatio-temporal gait analysis during a single task and during performance on a motor, a cognitive, and a visual-fixation dual-task. The dual-task effect was a measure of interference of the concurrent task on gait speed, stride length (a measure of gait performance), and stride time variability (a measure of automaticity and steadiness). RESULTS: Overall lower gait speed, shorter stride length, and higher stride time variability were noted in FGDs compared to healthy controls (for all, p < 0.019). The was a significant effect of group and Task × Group interaction for the dual-task effect on gait speed (p = 0.023) and stride length (p = 0.01) but not for stride time variability. CONCLUSION: Poorer gait performance and less automaticity and steadiness were noted in FGDs. However, dual tasking affected gait performance but, unlike different neurological diseases, not automaticity and steadiness compared to controls. Our findings shed light on higher-level gait control mechanisms in FGDs and suggest stride time variability could be a diagnostic and prognostic biomarker.